Method and apparatus for vulcanizing sponge rubber articles



NW. 11 1924. -1.51s,475

J. O. GOODWIN METHOD AND APPARATUS FOR VULCANIZING SPONGE RUBBER ARTI CLES Filed Aug. 14 1922 j v a 1/ 45 heat insulation in Patented Nov. 11, 1924.

UNITED STATES PATENT OFFICE.

J'OHIiT O. GO'ODWIN, OF AKRON, OHIO, ASSIGNOR TO THE B. F. GOODRICH COMPANY, or

' NEW YORK, N. Y., A CORPORATION OF NEW YORK.

METHOD AND APPARATUS FOR VULCANIZING SPON RUBBER ARTICLES.

Application fiJed August 14, 1922. Serial No. 581,577.

To all whom it may aonaem:

Be it known that I, JOHN O. GoonW'IN, a citizen of the United States, residing at Akron, in the county of Summit and State of Ohio, have inventeda certain new and useful Method and Apparatus for Vulcanizing Sponge Rubber Articles, of which the following is a'specification.

This invention-relates to means for vulcanizing sponge-mbber articles such, for example, as blocks or slabs of hard, cellular rubber adapted for heat insulation in refrigerators; Sponge rubber is ordinarily made by placing. the blank in a mold cavity having a volume greater than its own, applying vulcanizing heat and allowing the stock to swell and this method does not always give sharp outlines particularly when the stock is sulphur- 2 ized for making hard cellular rubber, and if the blank is made broad enough in one plane to fill out to the sides of the cavity before reaching the top of said cavity, the top surface will present a-more or less wrinkled I and folded appearance in the finished article.

- My invention aims to overcome these difficulties and it consists in the method and apparatus hereinafter claimed, of which a 80 simple embodiment will now be described.

Of the accompanying drawings, Fig. 1 is a perspective view, partly broken away and in section, showing a mold constructed according to and adapted to carry out my in- 85 vention, with the blank of sponge-rubberforming stockin place'therein.

Fig. 2 is a cross-sectionof the mold showing the stock expanded to its ultimate volume.

Fig. 3 is a perspective view of the finished product. Y In the drawings, 10 is the finished product inthe form of a rectangular prism,block or slab of cellular hard rubber, suitable for refrigerators. 11 is the vulcanizing mold comprising a metal frame 12 forming four sides of the molding cavity, a bottom plate 13 forming the lower side of the molding cavity, a .removable cover 14 o (which could be substituted bythe top platen of the vulcanizing press), and a rectan-.

wall is 10 of the fill the cavity. It is found that 'ifying substance in the stock gular floating plate 15 slidingly fitted within the opening of the frame 12, with but slight clearance from the sides thereof and forming the top wall of the molding cavity. There is thus provided a molding cavity having six rigid walls, of which the top movable to enlarge the volume of said cavity conformably with the expansion of the stock up to a predetermined limit.

In the operation of my invention a blank sponge-rubber stock, having substantially the same shape and horizontal dimensions as the molding cavity is placed in the bottom of said cavity, and the floating mold plate 15 is placed thereon, as indicated in Fig. 1, so that the stock substantially fills said molding cavity. The'cov er is then applied and the mold is placed between the platens of a hot-plate press and heat is applied, or the mold is clamped together and placed in open steam, which causes the gasto expand the rises until it latter. The floating plate 15 plate 14 and the vulcanizamects the cover tion then continues at fixed volume, said floating plate serving to form a smooth top surface on the finished article in place of the wrinkled surface which has heretofore been'encountered in attempting to-mold the blocks 10 with sharp outlines. After the vulcanization is complete, the mold is opened and the block 10 removed therefrom.

It will be understood that various modifications may be made within the scope of my invention.

I claim:

1. The method of molding a sponge rubher article which comprises contacting the blank on all sides with rigid walls, and expanding so contacted. I

2. The method of molding a spongerubher article which comprises inserting, in an expansible, rigid-walled vulcaniaing cavity,

a blank which substantially fills said cavity, the cavlty heating the blank while allowing to enlarge conformably with the expansion of the blank up to a predetermined volume, and then arresting further expansion while completing the vulcanization.

3. A rubber-vulcanizing mold having a .90 and vulcanizing it by heat 'while' rigid wall adapted automatically to yield to the expansion of the contents, and means for limiting the yielding movement.

4. A mold for vulcanizing a, sponge-rub- 5 her article, said mold including a floating plate forming the top wall of the molding cavity.

5. A mold for vulcanizing a sponge-rubher article, said mold having parallel, Ver- 7 tical side Walls, a bottom Wall in fixed re-- lation thereto, and a floating top Wall substantially filling the space between said side .Walls. 

